In 1948–1949, the city of berlin was blockaded by soviet forces. which sectors of the city were supplied by the airlift?

The Berlin AirliftWhen Germany was divided into zones at the end of World War 2, Berlin was divided into four sectors - one Soviet, one American, one British and one French. Geographically, Berlin was situated deep inside the Soviet Zone of Germany. In June 1948, following various disagreements between the West and the Soviet Union, Stalin had all surface links between West Berlin and the western zones of Germany cut. West Berlin (with a population of about two million) was in effect placed under a siege which is usually referred to as the Berlin Blockade. The point of the blockade was to try to force the Western countries   out of Berlin. (The immediate trigger was the introduction of the new currency, the Deutsche Mark, in West Berlin as well as West Germany).Much to the surprise

Idont know which one is right   but i know that c is wrong and a might be wrong